Typescript breakpoints with VSCode

Question

I've this Yeoman scaffolded project from the generator-express-no-stress-typescript template. I need to debug it, as in "step through the typescript code" with Visual Studio Code (and no, console.log() is not enough for me).

As per the docs I only need to issue

npm run dev:debug

and then attach VSCode. Here is the problem: if I do that, VSCode can't bind the breakpoints. If I make the debugger stop on the first execution line ("stopOnEntry": true), it stops in the generated JavaScript code instead of the source TypeScript code, and/but the filename in the tab title shows "index.ts" (not .js) in italics.

Here is the dev:debug script target in package.json:

"dev:debug": "nodemon --exec \"node -r ts-node/register --inspect-brk\" server/index.ts | pino-pretty",

and here is the "Attach" configuration in my launch.json:

    {
        "name": "Debug (Attach)",
        "port": 9229,
        "request": "attach",
        "cwd": "${workspaceFolder}",
        "sourceMaps": true,
        "skipFiles": ["<node_internals>/**"],
        "type": "node",
        // "outFiles": ["${workspaceFolder}/dist/**/*.js"],
    },

Since this did not work, I tried a few other tutorials out there, and one (I can't remember which one) made me add the following configuration to my launch.json:

   {
       "name": "Run and debug",
       "program": "${workspaceFolder}/server/index.ts",
       "request": "launch",
       "skipFiles": [
           "<node_internals>/**"
       ],
       "type": "node",
       // "outFiles": ["${workspaceFolder}/dist/**/*.js"],
       "runtimeArgs": ["-r", "ts-node/register", "--preserve-symlinks"],
       "runtimeExecutable": "node",
       "args": ["--inspect", "${workspaceFolder}/server/index.ts"],
       "cwd": "${workspaceFolder}",           
   }

This seemed promising at first, but then, when I tried it, it stepped through JS code instead of TS, just like the "Debug (Attach)" configuration above.

Here is the generated JS code that the debugger uses to trace execution. Please note that it contains the sourcemap in the commment at its end.

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
var _a, _b;
Object.defineProperty(exports, "__esModule", { value: true });
require("./common/env");
const server_1 = __importDefault(require("./common/server"));
const routes_1 = __importDefault(require("./routes"));
const models_1 = __importDefault(require("./api/models"));
const port = parseInt((_a = process.env.PORT) !== null && _a !== void 0 ? _a : '3000');
const syncdb = ((_b = process.env.SYNC_DB_SCHEMA_ON_STARTUP) !== null && _b !== void 0 ? _b : 'false') === 'true';
if (syncdb) {
    models_1.default.sequelize.sync({ force: true }).then(() => {
        console.log("DB Aggiornato");
    }).catch((err) => {
        console.log("Errore", err);
    });
}
exports.default = new server_1.default().router(routes_1.default).listen(port);
//# sourceMappingURL=data:application/json;charset=utf-8;base64,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

I decoded the base64 sourcemap and it seems to contain the correct paths to my sources and even a copy of the source code:

{"version":3,"file":"/home/lucio/myapp/server/index.ts","sources":["/home/lucio/myapp/server/index.ts"],"names":[],"mappings":";;;;;;AAAA,wBAAsB;AACtB,6DAAqC;AACrC,sDAA8B;AAC9B,0DAA8B;AAC9B,MAAM,IAAI,GAAG,QAAQ,CAAC,MAAA,OAAO,CAAC,GAAG,CAAC,IAAI,mCAAI,MAAM,CAAC,CAAC;AAGlD,MAAM,MAAM,GAAG,CAAC,MAAA,OAAO,CAAC,GAAG,CAAC,yBAAyB,mCAAI,OAAO,CAAC,KAAK,MAAM,CAAC;AAE7E,IAAI,MAAM,EAAE;IACR,gBAAE,CAAC,SAAS,CAAC,IAAI,CAAC,EAAE,KAAK,EAAE,IAAI,EAAE,CAAC,CAAC,IAAI,CAAC,GAAG,EAAE;QACzC,OAAO,CAAC,GAAG,CAAC,eAAe,CAAC,CAAC;IACjC,CAAC,CAAC,CAAC,KAAK,CAAC,CAAC,GAAQ,EAAE,EAAE;QAClB,OAAO,CAAC,GAAG,CAAC,QAAQ,EAAE,GAAG,CAAC,CAAA;IAC9B,CAAC,CAAC,CAAC;CACN;AAGD,kBAAe,IAAI,gBAAM,EAAE,CAAC,MAAM,CAAC,gBAAM,CAAC,CAAC,MAAM,CAAC,IAAI,CAAC,CAAC","sourcesContent":["import './common/env';\nimport Server from './common/server';\nimport routes from './routes';\nimport db from './api/models';\nconst port = parseInt(process.env.PORT ?? '3000');\n\n\nconst syncdb = (process.env.SYNC_DB_SCHEMA_ON_STARTUP ?? 'false') === 'true';\n\nif (syncdb) {\n    db.sequelize.sync({ force: true }).then(() => {\n        console.log(\"DB Aggiornato\");\n    }).catch((err: any) => {\n        console.log(\"Errore\", err)\n  

Here is my tsconfig.json, just in case it matters:

{
  "compileOnSave": false,
  "compilerOptions": {
    "inlineSourceMap": true, // added after answer below, still doesn't work
    "target": "ES2019",
    "lib": ["ES2020"],
    "strict": true,
    "module": "commonjs",
    "esModuleInterop": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "declaration": true,
    "moduleResolution": "node",
    "useUnknownInCatchVariables": false,
    "noImplicitAny": true,
    "noImplicitThis": true,
    "strictNullChecks": true,
    "noUnusedParameters": true,
    "noUnusedLocals": false,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": false,
    "strictPropertyInitialization":false,
    "alwaysStrict": true,
    "outDir": "dist",
    "typeRoots": ["node_modules/@types"],
    "resolveJsonModule": true,
    "baseUrl": "."

  },
  "include": ["server/**/*.ts", "server/api/models/index.ts"],
  "exclude": ["node_modules", "./test/", "./dist"]
}

And here is the output of npx ts-node --showConfig (after beautifulcoder's comment to his answer)

{
  "ts-node": {
    "cwd": "/home/lucio/myapp",
    "projectSearchDir": "/home/lucio/myapp",
    "project": "/home/lucio/myapp/tsconfig.json"
  },
  "compilerOptions": {
    "target": "es2019",
    "lib": [
      "es2020"
    ],
    "strict": true,
    "module": "commonjs",
    "esModuleInterop": true,
    "skipLibCheck": true,
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "useUnknownInCatchVariables": false,
    "noImplicitAny": true,
    "noImplicitThis": true,
    "strictNullChecks": true,
    "noUnusedParameters": true,
    "noUnusedLocals": false,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": false,
    "strictPropertyInitialization": false,
    "alwaysStrict": true,
    "outDir": "./.ts-node",
    "typeRoots": [
      "/home/lucio/myapp/node_modules/@types"
    ],
    "resolveJsonModule": true,
    "baseUrl": "./",
    "inlineSourceMap": false, // PLEASE NOTE: this is false even after I added `"inlineSourceMap": true` in tsconfig.json above
    "inlineSources": true,
    "noEmit": false
  }
}

I've scaffolded a new minimal example generator-express-no-stress-typescript project, following the documented procedure again. e.g.

$ npm install -g yo generator-express-no-stress
$ yo express-no-stress ts-debug-test

and choosing "OpenAPI 3" over "Swagger 2" when asked, which is what I did with the real project when I scaffolded it the first time. If you need a minimal example showing the problem you can do that too or you can find mine at GitHub, if you prefer. I've only added my launch.json to it and you only need to set a breakpoint at the first meaningful line of code.

So now I don't know what to do next in order to debug my code... any clues?

Answer 1

The problem was being caused (the real bug was being triggered) by a symlink in the path where I store my project, e.g.

/home/lucio/myapp -> /home/lucio/workspace/vscode/myapp

The real bug is in VSCode, here.

The straghtforward workaround is to avoid symlinks in the project folder path.